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John Honovich

We could potentially do another mode / tool that shows camera height positioning effects. I am not sure we can do it on the current onebut we'll think more about this.

Btw, another calculator I've been considering adding is F stop comparison, something that surveillance people often have troubles assessing (e.g., what's the difference between a camera/lens with f1.2 versus one with f/2.4).

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Rukmini Wilson

Works better with more options than any of the ones I've used. Good job!

One question: Maybe I'm overlooking how to do it exactly, but let's say you have a problem like the seminal 'View a Face at 3000M'. One where there is no target horizontal FOV but only a ppf requirement ~50 (?) and a distance to target. And for greater applicability let's assume only 100ft , not 3000M, for distance to target. What's the best way to find out what your choices are among the multiple solutions in three unknowns (FL,SS,RES). Just start plugin' each one and stop when your out of range?

@Ari, not quite the same as a mobile app, but the calculator seems to work fine in safari on ios, so iphone will work, of course its kinda small. :(

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Rukmini Wilson

Interesting that small pixel size is not all bad; starting with the default values in advanced mode and changing the resolution to 1080P, and then alternating between 1/1.8" and 1/4" sensor size doubles the ppf, at the expense, of course of FOV width.

I imagine you will point out that this is backwards and not that useful because we have less choice over imager size, than say lens or camera placement, since it is tied to the camera, and we are choosing cameras based on a multitude of other factors. I know that, but still its interesting to note.

'how wide an area can I cover?' Speaking of which, I think that's broken.

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John Honovich

"I imagine you will point out that this is backwards and not that useful because we have less choice over imager size"

Yes, than you for anticipating my response. Not only do you have less choice, the practical range is far less than what you tried. Most surveillance camera imagers today are between between 1/2.5" and 1/3" (including Full HD cameras).

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John Honovich

Rogier, we have plans to allow toggling between imperial and metric units. Insurveillance, ppf seems to be widely used even outside the US, so that's why we started with that. Will add the toggle in August. Thanks.

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Carl Lindgren

By the way, one calculator I would like to see is something that shows what you can see from certain angles and distances. For instance, if we want to see the faces of slot machine(s), I typically use my arm or a stick which I sight along to determine the correct mounting location for a camera.

Through trial and error, I've found that 45 degrees +/- ~10 degrees from the face of slots gives adequate coverage but it's tough to pass that trick along. Most people can't picture the results in their heads. A graphic would be ideal and I suppose I could take a bunch of pictures from various angles to show a comparison but....

A good part of the consideration includes obstruction of the face by objects and people: too high an angle and you lose the ability to see the display. Too low and the display can be blocked by the customer. Other considerations are focus variance. Too large a lens-to-object distance variation between machines and you can't get them all in focus simultaneously.

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Rukmini Wilson

What's the best way to change the focal length and have it only recalculate the ppf leaving everything else alone? And vice versa?

I see that you have an upper limit on focal length in-place. I've heard there is some limitation with these linear calculators and long-lens lengths, but I've never learned the details. Is this why the 500mm cap exists, and if so can you explain what causes the problem?

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John Honovich

What's the best way to change the focal length and have it only recalculate the ppf leaving everything else alone? And vice versa?

The focal length, by definition, changes the AoV, so I don't understand why it would make sense to only recalculate the ppf. Am I missing something?

The 500mm cap is the Rukmini feature :) We simply don't have enough experience testing super long lenses and worry that other issues (atmospheric conditions, depth of field problems, etc.) will make the PPF previews images inaccurate. it's an edge case, and if there is a lot of demand for 500mm+, we can always review, do testing, update appropriately.

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Rukmini Wilson

One to consider when you run out of other enhancements: Ability enter two focal lengths to simulate the range of a vari-focal lens. Then automatically zoom, or drag, between the two to show corresponding fov and ppf changes.

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John Honovich

We are actually going to implement this when we add in camera models. There will be a dropdown list of models. Let's say the user picks an Axis P3364-V. We'll know it's a 1MP with a range of 49-109° AoV. We'll then lock in the calculator so it only shows that AoV range and no more than the camera's max resolution.

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Carl Lindgren

Focal length appears to override everything in Advanced. For instance, when I enter distance as 15' and try to enter a horizontal field of view of 6', it keeps changing distance to 3' while keeping the lens 2mm.

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Carl Lindgren

OK, well I have pretty much always used lens calculators by plugging in distance and desired HFoV and calculating lens focal length. Guess I'll stick with my handy dandy widget, though it is optimized for 4:3 and only covers 1/4", 1/3" and 1/2":

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Carl Lindgren

Hah! Every disagreement can be construed that way. Seriously, the issues I have with my "widget" are that it doesn't account for 16:9, only covers 1/4", 1/3" and 1/2" imagers and it automatically compensates for 10% CRT overscan.

Ari, I have one of those too but it is older and only has 1/3" to 1" graduations and doesn't go "wide" enough for many of our applications.

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Rukmini Wilson

This is similar to my question regarding PPF, i.e. what part of the wheel moves, and your answer would be the same I believe. (polynomials with two unknowns)

Or we could add in more advanced controls someplace else...

But I like the layout and the simplicity of the interface the way it stands, and think you could accommodate full freewheeling 'what-if-ness' by adding a lock or unlock icon (smaller than shown) next to the edit boxes to constrain the values:

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